A snap fastener closure is a type of attachment system that has a multiple-part socket part or female part with a housing for the male part, which housing has an insertion hole. A push plate made of resilient or elastic material is arranged in this housing. This push plate is forked and is guided by its two plate legs into a shared channel of the housing. The plate legs are divided into portions which differ from one another in extent, and the plate legs have a lock portion where the plate leg is smaller than a closing head of the male part. This characterizes the lock portion of the push plate. However, this lock portion also allows an elastic expanding or spreading movement and is therefore also a coupling portion to enable the closing head of the male part to be inserted through the insertion hole in the housing. The push plate is acted upon by a spring and can be pushed in until there is a large distance between the plate legs at the insertion hole and makes it possible for the male part to be pulled out axially.
In the known snap fastener closure of this kind (CH 442 833 A), the two plate legs have the same length and are supported by their ends at the two sides of an angled projection in the housing. When the push plate is pressed into the housing, the two leg ends slide at the sides of the angle which are inclined relative to one another in a mirror-inverted manner and the two plate legs spread apart in the lock portion until the closing head of the coupled in male part, behind which closing head the plate legs engage, can be removed from the housing of the female part. The two plate legs are connected in the transition to the shared actuating end by a circular arc which increases the overall width of the push plate and improves the spreading elasticity of the leg ends. This widened transition limits the pushing out of the push plate and requires a correspondingly widened channel in the housing.
Because the overall width of the push plate is not uniform, a multiple-part housing is required. Therefore, in order to produce the female part, an expensive individual production of two housing parts and a complicated, time-consuming assembly is required. Although the distance between the two plate legs in the arc-shaped transition is widened, this region cannot be made use of for uncoupling the male part because, when pressing in, the push plate is moved axially to such a limited extent that the male part still remains in the effective lock portion for coupling. In this snap fastener closure, the spreading elasticity used between the two plate legs is the same as that which, together with the angular projection, generates the push-out force. The plate legs are accordingly under a constant force acting in the spread-out direction, which force can lead to material fatigue over the course of time. However, reduced elasticity threatens the dependability of the engagement of the male part in the female part.